As shown in FIG. 1, it is presently known to use a nanoplasmonic resonators (NPR) 2 in the form of a thin dielectric layer 4 (e.g. SiO2) sandwiched between two metallic nanodisks 6 on a quartz substrate 8 to enhance SERS (Surface Enhanced Raman Scattering) Raman intensity for the detection of protease and enzyme activity. The NPR 2 results in SERS hot-spots at desired locations and in small dimensions, allowing for multiplexed high-throughput detection and lab-on-chip applications. The resonance frequency of the NPR can be precisely tuned by varying the dielectric layer thickness and the aspect ratio of the NPR. Such NPR and SERS techniques are disclosed in U.S. Pat. No. 8,685,743, which is incorporated herein by reference.
The nanodisk NPRs have been patterned on quartz substrates by electron beam lithography (EBL). However, EBL techniques are time consuming and expensive. Moreover, while disk shaped NPRs have shown to enhance the Raman intensity by a factor of over 6×106, further Raman intensity enhancement is needed.
There is a need for improved techniques in forming NPRs, and there is a need for different NPR structures that further enhance the Raman intensity.